there are around 100M non-zero entries. The sequence file size is not that huge, around 300M bytes.
i'll check out your other options to see what is wrong. - Lei On Fri, Sep 14, 2012 at 2:23 PM, Dmitriy Lyubimov <[email protected]> wrote: > most importantly, what's your number of non-zero elements. (or input > sequence file size). > > On Fri, Sep 14, 2012 at 2:19 PM, Dmitriy Lyubimov <[email protected]> > wrote: > > Q job is actually the fastest and map-only.I'd say you drop all the > > optional parameters (including p) and use mahout 0.7. > > > > Actually reducing split size is unlikely to help. Default split should > be fine. > > > > i'd say running -k 10 on any sized input should result in Q mapper > > task running in at most couple of minutes. > > > > using -k200 -p100 is fairly ambitious (mapper task running time will > > scale a little worse then proportional to k+p). > > > > if you use -q1 you will likely to have more problems with ABt job and > > that may require some memory tuning... > > > > otherwise check the usual things -- memory, cluster capacity (do you > > actually have capacity running 100 mappers? Do they have at least 1G > > of RAM on -Xmx without scratching the swap? Are you seeing GC > > thrashing? etc.) > > > > That said your problem doesn't seem too big (judging from 100 mappers > > with a regular split size, that should be ok). with -k 100 and default > > p you should expect single q task to run about 20-25 minutes, > > depending on your hardware. It is cpu-bound (or rather, mostly > > fpu-bound, assuming you tackled memory issues etc.) > > > > > > On Fri, Sep 14, 2012 at 1:24 PM, lei tang <[email protected]> wrote: > >> Hi, > >> > >> I am using mahout's SSVD (stochastic SVD) to factorize a huge sparse > >> matrix (around 30M x 1M). I used a modified script of > >> > http://bickson.blogspot.com/2011/02/mahout-svd-matrix-factorization.html > >> to store the input matrix with <key, value> pairs being integer, and > >> vectorwritable (in particular, SequentialAccessSparseVector). Should I > >> change to RandomAccessSparseVector? > >> > >> I managed to run mahout SSVD with the following specification. > >> mahout ssvd -Dmapred.max.split.size=1000000 -i mf/tr_full.seq -o > >> mf/out_full -k 200 -p 100 -r 100000 -U true -V true -t 20 --tempDir > mf/tmp > >> > >> I specified the max split in order to have more mappers. However, the > >> first Qjob seems not moving. After 1 hour, it is still 12% with 100 > >> mappers. Is this expected? Should I change any parameter? > >> > >> Any suggestion is highly appreciated. > >> > >> - Lei > >> P.S. I'm also reading the docs from > >> https://issues.apache.org/jira/browse/MAHOUT-376 in hope that I can > figure > >> out why it is so slow. >
